Second ever July zero?

Outcome: Didn't happen; squeaked in by a whole centimetre

In 61 years of measuring snow depths at Spencers Creek, midway between Perisher Valley and Thredbo, the only zero depth that Snowy Hydro has ever recorded in July was way back on 3 July 1957. With the collapse of this week’s promising snow weather system, we are now withing sight of just our second ever July zero at the usual weekly measure on Thursday, 2 July.

Model forecasts between this week’s fizzer and the first July measure are for a huge high pressure system to dominate the continent, with the circumpolar flow pushed far to the south:

US weather model GFS’s prediction for Monday next week, from metvuw.com

The only positive is that snowmaking conditions should be good for much of the coming week, for those who appreciate the artificial stuff. Nearer to the day a northerly feed may arrive in the wake of the high, with the possibility of relatively warm, snowpack-melting rain.

Here’s how things looked at Spencers Creek as at last Thursday’s zero natural snow depth:

Spencers Creek snow depth, from Snowy Hydro

Spencers Creek snow depth, from Snowy Hydro

The 1957 zero does not show there because the background points are interpolated weekly depths (for Thursday, the usual measurement day), so that the coverage is even over time. The 1957 zero was recorded on a Wednesday, and the next measure was a healthy 70.9 cm on Friday of the following week, making an interpolated 7.9 cm for Thursday 4 July 1957 the lowest plotted July point. The next lowest measured July depth was 9.9 cm on 24 July 1959, which had easily the thinnest July overall.

2 comments to Second ever July zero?

  • D

    Gergs – just turned up that there may well have been zero in 1957. July 3 was the first ob and it had zero snow that year in the Snow Mt’s file. PM me for more details.

    • Gerg

      Yep, thanks, you’re right; now corrected above.

      It’s right there in my database too. I missed it because it doesn’t plot in the snow depth scatter plot, above. That’s because July 3, 1957 was a Wednesday, and the plot is of resampled Thursday depths (to enforce even temporal weighting in the scatter). So the plotted point is a linear interpolation between zero on Wednesday July 3 and 70.9 cm on Friday July 12. Whoops…

      I’ve now checked properly — there are no others. The next lowest is 9.9 cm on 24 July 1959. The only months which genuinely have no zeros are August (lowest 37.8 cm on 2 August 1973) and September (22.7 cm on 29 September 2006).

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